Plasma display panel including a component provided between front and back plates thereof

ABSTRACT

The invention relates to a method of disassembling a plasma display panel (“PDP”) for reutilization. A first method uses a component, which is thermally not contractible at a softening temperature of bonding material used for hermetically bonding a front and back plates, and positioned between the plates. The above component maintains or widens a space provided between the two plates when the PDP is heated, thereby facilitating disassembly of the PDP. The invention also provides a groove on a surface of either or both plates for communicating the bonding material to an exterior of the PDP. Softened bonding material can be drawn out or absorbed through the groove. Heating and cooling of the PDP may be made through a laminated graphite sheet placed on a surface of the PDP for uniformalizing thermal distribution. A second method separates a PDP into two plates by immersing the PDP in etching solution capable of selectively dissolving only lead glass, and melting the bonding material. A groove is provided between the perimeter of an image display screen and a bonded portion in order to prevent etching solution from permeating into the screen area. The groove is formed on the substrates in parallel with a longitudinal direction of electrodes. The separated plates are refurbished by restoring a deteriorated or defective portion into the original condition for use in manufacturing a new PDP.

FIELD OF THE INVENTION

The present invention relates to recycling of a plasma display panel(hereinafter referred to as “PDP”) employed in a computer terminal, awall-hung television, and the like. More particularly, the inventionrelates to a method of disassembling a PDP, as well as a structure of aPDP and a method of heating the PDP, with which the disassembling ismade efficiently.

BACKGROUND OF THE INVENTION

PDPs are self-luminous displays that are easily viewable from a widerange of angles, advantageously very thin and large in screen area size.For these reasons, PDPs are becoming ever more popular as new displaydevices that are replacing cathode ray tubes (CRTs). Sincesurface-discharge type AC PDPs, in particular, are easy to manufacture,and have a long operational life, many of them have been developed,manufactured, and marketed by numerous manufacturers.

As shown in FIG. 16, a PDP comprises a front plate 1 and a back plate 2consisting of a glass substrate 3 and provided on front plate 1 aresustain electrodes 5, a dielectric layer 6 and a protection layer 7.Back plate 2 consists of a second glass substrate 4 and provided on itare address electrodes 8, and barrier ribs 9. Further, phosphor 10 isprovided within the ribs 9. Both plates are bonded together along theirentire periphery with bonding material 13.

An ordinary manufacturing process of the PDPs can be broken down intothe steps of (a) producing front plates, (b) producing back plates, (c)assembling, sealing, vacuuming and gas charging.

When producing a front plate 1, sustain electrodes 5 are formed on aglass substrate 3, and a dielectric layer 6 made of lowtemperature-melting glass containing lead oxide is formed on glasssubstrate 3 by screen-printing and sintering.

A back plate 2 is produced by forming address electrodes 8 on a glasssubstrate 4, and ribs 9 between the address electrodes 8 with lowtemperature-melting glass containing lead oxide. Phosphors 10 of red,green and blue colors are formed between the ribs 9.

The front plate 1 and the back plate 2 are assembled together by placingone over the other, and hermetically bonding them with bonding material13 containing lead oxide. A PDP is finally completed by charging it witha rare gas containing Xe, after a sufficient discharge of impure gasesby vacuum-pumping an interior, while heating the assembled PDP.

As described, the PDPs use a considerable amount of lowtemperature-melting glass containing lead oxide. Low temperature-meltingglass is used for the dielectric layer in the front plate, the ribs inthe back plate, and the bonding material for hermetically bonding thefront plate with the back plate, to name a few examples. These PDPs aredisposed of, if any flaw is detected in them during the manufacturingprocess, or when they have lost their usable life in their end useapplication. However, they cannot be discarded like ordinary wasteproducts, but they are required to be treated properly by establishmentsspecializing in industrial waste disposal, because they contain lead.

Although there is a way to recycle the discarded PDPs as glass culletfor manufacturing glass, the discarded PDPs propound a problem ofdegrading quality of glass, if mixed with raw glass material, since theycontain lead oxide.

Additionally, there is a need for taking urgent measures againstdisposal of products containing lead components, in view of the recentglobal environmental issues and strict regulations against lead waste.

SUMMARY OF THE INVENTION

The present invention utilizes a thermal action and a chemical action ina process of disassembling the above-described PDPs.

A first method adopts a component, that does not contract thermally at asoftening temperature of a bonding material used for hermeticallybonding a front plate to a back plate, and is positioned between the twoplates at the front and back. And, the two plates are separated with theuse of this component. Further, the above-cited component maintains agap with either one of the front plate and the back plate under anambient room temperature, but the component either remains unchangeddimensionally, or expands when heated, thereby the component facilitatesdisassembly of the PDP.

Furthermore, the present invention provides a groove on at least one ofthe surfaces of the front plate and the back plate, for communicatingthe bonding material to an exterior of the PDP. A softened bondingmaterial can be drawn out or absorbed through the groove. Anotherfeature of the invention is to uniformly heat and cool the PDP with alaminated graphite sheet provided on either an upper surface or a sidesurface of the PDP during the heating process.

A second method of the present invention is to separate a PDP into twoglass substrates by immersing the PDP in etching solution thatselectively dissolves only lead glass, and melts the bonding material.

For this method, a groove is formed in a space between a perimeter of animage display screen and a bonded portion, in order to prevent theetching solution from invading into the display area in a center of thePDP by a capillary phenomenon. In either case of the front plate and theback plate, the groove is formed in a direction parallel with alongitudinal direction of electrodes formed on the substrates.

The front plate and the back plate which are separated through theforegoing process are refurbished in a way that a deteriorated portionor a defective portion regains an original function. The refurbishedfront plate and back plate can be reutilized to make a PDP byhermetically bonding them again. Therefore, the handling and disposal ofdangerous lead materials may be significantly reduced thereby materiallyenhancing the quality of the environment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a PDP;

FIG. 2 illustrates a plan view of a PDP and a direction of an applyingpressure to the same;

FIG. 3 illustrates a side view of a PDP and a method of applying apressure to the same;

FIG. 4 is a cross-sectional view illustrating a PDP of the presentinvention;

FIG. 5 is a cross-sectional view of the same PDP of the presentinvention illustrating a state wherein it has been placed in a hightemperature ambient;

FIG. 6 is a cross-sectional view illustrating a PDP of the presentinvention;

FIG. 7 is a side view illustrating a PDP of the present invention;

FIG. 8 is a cross-sectional view illustrating a PDP provided withlaminated graphite sheets on its surfaces, in a method of separating thePDP of the present invention;

FIG. 9 is a cross-sectional view of the same PDP illustrating adirection of lamination of the laminated graphite sheet in a step ofheating the PDP of the present invention;

FIG. 10 is a plan view illustrating a PDP of the present invention;

FIG. 11 is a cross-sectional view of the same PDP of the presentinvention, illustrating an arrangement of grooves;

FIG. 12 is another cross-sectional view of the same PDP of the presentinvention, illustrating an arrangement of grooves;

FIG. 13 is a cross-sectional view illustrating a front plate of a PDP ofthe present invention;

FIG. 14 is a cross-sectional view illustrating a back plate of the PDPof the present invention;

FIG. 15 is a general view illustrating a method of etching a bondedportion of a PDP; and

FIG. 16 is a cross-sectional view illustrating a PDP of the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments of the present invention will be describedhereinafter. FIG. 1 shows an exploded perspective view of asurface-discharge type AC PDP. The PDP comprises a front plate 1 and aback plate 2. The front plate 1 comprises sustain electrodes 5 forsustaining an electric discharge, a dielectric layer 6 provided over thesustain electrodes 5 and composed of low temperature-melting glasscontaining lead oxide, and a protection layer 7 composed of MgO, allformed on a glass substrate 3. The protection layer 7 of MgO has afunction of protecting the dielectric layer 6 from sputtering due toelectric discharge as well as a function of lowering a dischargevoltage.

The back plate 2 comprises address electrodes 8, ribs 9, and phosphors10 of red, green and blue colors, all formed on another glass substrate4. Material comprising the ribs 9 is low temperature-melting glasscontaining filler for maintaining its shape, and lead oxide. Both platesare held together and bonded along their entire periphery with bondingmaterial 13, in an actual PDP, although FIG. 1 illustrates the frontplate 1 and the back plate 2 as being separated from each other in orderto easily understand them. The bonding material 13 also consists of lowtemperature-melting glass containing lead oxide. The PDP is completedwhen it is charged with rare gas such as Ne gas containing severalpercent of Xe, after having hermetically bonded the front and backplates together with the bonding material 13, while expelling impuregases by vacuum-pumping an interior and heating.

Exemplary embodiments of the present invention will be describedhereinafter by referring to FIG. 1 through FIG. 15.

FIRST EXEMPLARY EMBODIMENT

Generally, a PDP has a portion where a front plate 1 and a back plate 2do not overlap completely, as shown in FIG. 2. This portion is mainlyused for leading terminals of address electrodes (not shown in the FIG.2).

Thus the PDP can be illustrated as in a side view of FIG. 3, if it isheld vertically and viewed from a direction of an arrow shown in FIG. 2.There is a space 101 underneath the front plate 1, as viewed in thisdirection.

Therefore, the front plate 1 and the back plate 2 can be separated whena downward force is applied to the front plate 1 with a depressing part102 provided on top of the front plate 1, as shown in FIG. 3, sincebonding material 13 softens if the PDP is heated to 450° C. or highertemperature, and more preferably at a temperature between 450° C. and550° C.

Although the depressing part 102 is provided on the front plate 1 in thepresent exemplary embodiment, the same result can be attained byproviding it on the back plate 2. Also, in the case that the front plate1 and the back plate 2 overlap entirely, a provision of a spacer standunder one of the panels can produce a space under the other panel,thereby the same result can be attained.

Furthermore, although the depressing part 102 is used for applying adownward force, in the described exemplary embodiment, the same resultcan be attained by other means such as pulling up one of the plates.Moreover, although the PDP is placed vertically in the describedembodiment, the same result can also be attained by placing the PDPhorizontally, and either pushing or pulling one side of at least eitherone of the front plate 1 and the back plate 2 horizontally.

SECOND EXEMPLARY EMBODIMENT

FIG. 4 is a cross-sectional view illustrating an essential portion of aPDP of the present exemplary embodiment. The PDP has a structure inwhich a front plate 1 and a back plate 2 are bonded together withbonding material 13. The bonding material 13 in this instance iscomposed of lead oxide and silicon oxide as primary components. Thefront plate 1 has a structure wherein sustain electrodes 5, dielectriclayer 6 and protection layer 7 are provided on a glass substrate. Theback plate 2 has a structure wherein address electrodes 8 and barrierwalls 9 are provided on another panel. Also, phosphors 10 are providedwithin spaces provided between the ribs 9. The bonding material 13 bondsboth plates along an entire perimeter of the PDP.

This causes the interior of the PDP to be hermetically sealed. The PDPis also provided with supporting components 22 between the front plate 1and the back plate 2. The supporting components 22 in this exemplaryembodiment are made of stainless steel, which generally has a thermalcoefficient of expansion between 1 and 2×10⁻⁵/K. The PDP is placed in ahigh temperature ambient of 450° C. or higher, and more preferably in atemperature range of 450° C. and 550° C. The supporting components 22expand thermally in this ambient, so as to widen a space between thefront plate 1 and the back plate 2.

On the other hand, the bonding material 13 softens in this hightemperature ambient, and it dissociates from the plates, when it becomesunbearable to an expanding force of the supporting components 22. As aresult, the PDP can be separated into the front plate 1 and the backplate 2 for reutilization.

In the present exemplary embodiment, although the supporting components22 are provided at an outer side of the bonding material 13, as shown inFIG. 4, the same effect can be attained so long as they are provided atany position between the front plate 1 and the back plate 2. Also, thepresent exemplary embodiment adopts the supporting components 22 made ofstainless steel. The bonding material 13 not only softens, but alsoflags in this high temperature ambient, so as to shrink in height asshown in FIG. 5. Therefore, the same result can be achieved, even if thesupporting components 22 are made of material having a small thermalcoefficient of expansion, e.g. ceramic such as silicon nitride, and thelike, instead of stainless steel.

Furthermore, although the present exemplary embodiment adopts astructure wherein the supporting components 22 are provided in advancebetween the front plate 1 and the back plate 2, they may be insertedbetween the front plate 1 and the back plate 2 immediately beforeheating the PDP for the purpose of separating the PDP in order to obtainthe same effect.

THIRD EXEMPLARY EMBODIMENT

FIG. 6 is a cross-sectional view showing an essential portion of a PDPof a third exemplary embodiment. In this exemplary embodiment, each ofsupporting components 22 has a gap 23 between it and front plate 1,whereas it maintains direct contact with back plate 2. The supportingcomponents 22 are made of stainless steel.

The gaps 23 disappear due to a thermal expansion of the supportingcomponents 22, when the PDP is heated to 450° C., which is a softeningpoint of bonding material 13. Further continuation of the heating causesthe supporting components 22 to produce a force of expansion, and thebonding material 13 dissociates from the plates when the adhesiveproperties of bonding material 13 becomes unbearable against this force.

Additionally, supporting components 22 are capable of separating the twoplates even if they produce only a small force of expansion, since thebonding material 13 shrinks in height as it flags, as shown in FIG. 5.

FOURTH EXEMPLARY EMBODIMENT

FIG. 7 illustrates a side view of a PDP. A back plate 2 is provided withgrooves 24 communicating bonding material 13 to an exterior of the PDP.The PDP is heated to a temperature of 450° C. or higher, and morepreferably at a temperature range of 450° C. and 550° C. The PDP is thenplaced in an atmosphere of reduced pressure while maintaining the heatedtemperature. This method draws out the bonding material 13 through thegrooves 24, since the bonding material 13 has been softened at theheated temperature, and the exterior of the PDP is surrounded by thereduced pressure.

Accordingly, the PDP can be separated into the front plate 1 and theback plate 2 for reutilization. In this exemplary embodiment, althoughthe bonding material 13 is removed by reducing a surrounding pressure ofthe PDP, the same effect can be achieved with an aid of a nozzle-shapedtool for drawing the bonding material 13 by suction. The same effect canalso be attained by inserting a metal mesh or a porous material such asalumina-ceramic into the grooves 24, so as to remove the bondingmaterial 13 by absorption or capillary action.

FIFTH EXEMPLARY EMBODIMENT

Laminated graphite sheets 25 are placed on a front plate 1 and a backplate 2, as shown in FIG. 8. The laminated graphite sheets 25 used inthis exemplary embodiment comprise a number of discrete graphite sheets26, which are stacked vertically in the same direction with the frontplate 1 and the back plate 2, as shown in FIG. 9 (the back plate 2 isnot shown in FIG. 9). The laminated graphite sheets 25 exhibit arelatively high thermal conductivity in a range of 10 to 87 W/m·K in an“A” direction, which is orthogonal to the direction of stacking, but arelatively low thermal conductivity in a range of 0.4 to 1.2 W/m·K in a“B” direction, which is the same direction as the stacking.

Accordingly, a distribution of temperature can be maintained uniformlythroughout surfaces of the front plate 1 and the back plate 2 situatedunder the laminated graphite sheets 25 shown in FIG. 8. As a result, thelaminated graphite sheets 25 can prevent the plates and associatedcomponents from cracks or similar damages, which may occur otherwisewhen heating the PDP. Such cracks and damages can occur due to a lack ofuniformity in temperature or a thermal shock in the substrates.

SIXTH EXEMPLARY EMBODIMENT

A PDP of the present exemplary embodiment is provided with a groove 12between a perimeter of an image display screen 11 and a bonded portionon at least either surface of a front plate 1 and a back plate 2, asshown in FIG. 10. This structure prevents etching solution from enteringinto the screen area by a capillary phenomenon.

In FIG. 10, the image display screen 11 is located in a center areawhere the front plate 1 and the back plate 2 intersect, and bondingmaterial 13 is applied in a boundary of intersection of the two panels.The groove 12 provided in the area between the bonded portion and thedisplay screen, as shown in FIG. 10, can prevent the etching solutionfrom advancing beyond the groove 12 to the screen side, even if theetching solution permeates through the bonding material 13, therebyprotecting the display screen.

The direction of the groove is parallel with a longitudinal direction ofelectrodes on the front plate 1, on which at least the electrodes and adielectric layer are formed. Providing the groove 12 in such directioncan facilitate lead-out or connection of the sustain electrodes toexternal terminals, since the electrodes and the groove 12 do not crosswith each other. Also, the direction of the groove 12, when provided onthe back plate 2, is parallel with a longitudinal direction ofelectrodes on the back plate 2. Providing the groove in such directionalso facilitate lead-out or connection of the address electrodes toexternal terminals, since the electrodes and the groove 12 do not crosswith each other.

The dimensions of the groove 12 in the present invention is describednow. In principle, the groove is more effective in preventing permeationof the solution by the capillary phenomenon, as the groove is made widerand deeper. If the groove is sized 1 mm in width and 0.5 mm in depth,for instance, it cannot prevent permeation of the etching solution intothe PDP, as the solution crosses over the groove.

However, the groove can prevent permeation, if it is deepened to 1 mmwhile keeping the same width of 1 mm. Besides, an addition ofsurface-active agent into the etching solution can effectively reduce arise of liquid level of the etching solution due to the capillaryphenomenon. In the case of a groove in a size of 1 mm in width and 0.5mm in depth, for instance, the groove can prevent permeation, if asurface-active agent is added into the etching solution, whereas thesolution crosses over the groove if it does not contain surface-activeagent.

A method of manufacturing a PDP will be described next.

Description of the front plate 1 is addressed. FIG. 13 illustrates across-sectional view of the front plate 1. A pane of ordinary soda limeglass having a thickness of 2.8 mm is used for a glass substrate 3, onwhich a groove 12 of 1 mm wide by 1.5 mm deep is cut at each side with adiamond cutter. The grooves may be made by other methods such as glassetching.

The grooves are to be oriented in parallel with a longitudinal directionof sustain electrodes 5. The sustain electrodes 5 are then formed in ashape of stripes with Ag or Cr/Cu/Cr on the glass substrate 3, afterprocessing the grooves as above. A dielectric layer 6 is formed next byprinting low temperature-melting glass containing lead oxide over thesustain electrodes 5.

A method of making a back plate 2 is described next. FIG. 14 illustratesa cross-sectional view of the back plate 2. A pane of soda glass havingthe same thickness of 2.8 mm is used for a glass substrate 4, on which agroove 14 of 1 mm wide by 1.5 mm deep is cut at each side with a diamondcutter.

The grooves are also oriented in parallel with a longitudinal directionof address electrodes 8. The address electrodes 8 are then formed in ashape of stripes with Ag or Cr/Cu/Cr on the glass substrate 4, afterprocessing the grooves as above. Ribs 9 are formed thereafter betweenthe address electrodes 8. The ribs 9 are formed by printing multiplelayers of low temperature-melting glass paste containing lead oxide by ascreen-printing method. Other methods may be used such as sandblasting,photosensitive paste, photo burying, compression molding, and the liketo form ribs 9. Phosphor 10 is then formed by screen-printing phosphorpaste between the ribs 9 on the substrate prepared as above.

General outlines of the grooves produced in the above steps are shown inFIG. 11 and FIG. 12. FIG. 11 and FIG. 12 respectively illustratecross-sectional views of the PDP as it is viewed from an “A” directionand a “B” direction as marked in FIG. 10.

A sealing method will be described hereinafter. The front plate 1 andthe back plate 2 are placed together, and sintered to bond themhermetically, afterward they are coated with bonding material 13 (glasspaste) near a boundary area of intersection between the two plates, asshown in FIG. 10. The hermetically bonded plates are vacuum-pumped toevacuate air sufficiently from the interior while heating them in anelectric furnace, and a mixture of Ne gas containing 5 vol % of Xe ischarged at a pressure of 500 torr (ca 67,000 Pa), in order to complete aPDP.

Described next is a method of recycling a PDP. First, the PDP alone isremoved from an apparatus by disconnecting it from a circuit board. Atube (not shown in the figures) used for vacuuming in the foregoing stepis pierced to bring the interior back to the atmospheric pressure. FIG.15 shows a general idea of immersing the PDP in etching solution 14 thatcan selectively dissolve only lead glass. As shown in FIG. 15, the PDPis immersed in the etching solution 14 to the extent that a liquid leveldoes not exceed beyond the groove 12, while keeping the PDP in aposition that the groove 12 on the substrate is parallel with the liquidsurface. When the bonding material on one side of the PDP is dissolved,the panel is rotated 90 degrees to continue etching of the remainingsides in the same manner.

One example of the etching solution is an aqueous solution of nitricacid and HBF₄. An aqueous solution of mineral acid is another kind, suchas sulfuric acid, hydrochloric acid, and the like may be used as analternative etching solution. Or, other chemical substances may be usedas long as they dissolve lead oxide, while not dissolving the substratesmade of soda lime glass. The front plate and the back plate are thusseparated after all four sides are etched in the described manner.

A method of refurbishing the separated front plate and back plate forrestoring the original performance by way of removing a deterioratedportion will be described now. A description pertaining to the frontplate is given first. Of all the parts comprising the front plate 1,protection layer 7 is the one that deteriorates the most during ordinaryoperation of the PDP. In a word, the protection layer 7 is sputteredduring long usage periods, even though it is made of MgO, which ishighly resistive to sputtering. This results in an exposure of an underlayer of dielectric substances, thereby increasing a discharge voltage.Although the layer of MgO reduces the discharge voltage because of itshigh emissivity of secondary electrons, the dielectric substances have arelatively lower emissivity of secondary electrons as compared to MgO,so as to require a high discharge voltage.

It is therefore necessary to remove the protection layer 7 from theseparated front plate and to reform a new protection layer 7 with MgO,in order to restore the performance. Dry etching such as chemicaletching with hydrochloric acid, sputter etching, and the like are someof the methods available for removing the protection layer 7. Electronbeam deposition, reactive sputtering, CVD method, screen-printing, andthe like are used to form a new protection layer of MgO in a thicknessof 0.5 μm to 1 μm.

A method of refurbishing the back plate is now described. A phosphor 10is the one that deteriorates mainly in the back plate 2 during use ofthe PDP. In a word, charged particles generated by plasma dischargecollide against the phosphor 10, and reduce luminous efficiency of thephosphor. Additionally, sputtered MgO deposits on the surface of thephosphor, and reduces transmissivity of the ultraviolet rays, so as tofurther decrease the luminous efficiency of the phosphor.

In order to restore the original performance, it is necessary to removethe phosphor 10 from the separated back plate, and to reform a newphosphor. Some of the methods available for removing the phosphorinclude blowing off of the remaining phosphor with pressurized gas,brush-cleansing or ultrasonic cleansing in organic solvent, and thelike. A combination of these methods may be used for removing of thephosphor 10. A new phosphor is formed thereafter with such methods asscreen-printing, ink-jet printing, and the like.

Using the refurbished front plate and back plate, a PDP is completed byhermetically bonding them again, and charging an interior of the bondedpanels with mixture of Ne gas containing 5 vol % of Xe. The PDP asrefurbished in the foregoing process is not at all inferior to a newPDP, and it exhibits totally identical performance to the brand-new PDP.

SEVENTH EXEMPLARY EMBODIMENT

Described hereinafter is a seventh exemplary embodiment, hereinsurface-active agent is added into etching solution for leadoxide-contained glass.

A PDP is immersed in solution, which is prepared by adding 10% ofneutral detergent in the etching solution used in the sixth exemplaryembodiment. The etching solution added with surface-active agent canreduce a level of permeation that the solution rises up into a spacebetween the two plates from the liquid surface, when compared to thecase using the etching solution with no additive.

For this reason, it does not require close watching for a parallelism ofthe groove 12 with respect to a liquid surface during the immersion.Work efficiency is thus improved. There are cases where etching solutionpermeates beyond the groove if the groove is not kept almost parallelwith the liquid surface, when the surface-active agent is not added.

There is also an effect of allowing a reduction in width and depth ofthe groove to be formed on the substrates. If the groove is in a size of1 mm in width and 0.5 mm in depth, for instance, it cannot preventpermeation of the etching solution, as the solution crosses over thegroove. However, addition of the surface-active agent prevents theetching solution from permeating into an interior of the PDP.

After separation, the plates are refurbished by implementing the methodsas have been described in the sixth exemplary embodiment.

As has been described, the present invention realizes separation of theplates, thereby providing an advantageous effect of reutilizing them,although plates of the prior art PDPs have not been recycled before. Thepresent invention also provides an advantageous effect that the PDP iscapable of resisting against heating without resulting in cracks andfracture, even if it is heated rapidly during a process of separation.

Further, the plates can be reutilized for new PDPs by collecting oldPDPs from the marketplace after they have lost their originalperformance over the long term of service. That is, a dielectric layerformed on the front plate and ribs formed on the back plate can be usedjust as they are. This helps to reduce manufacturing steps in theproduction of PDPs, as well as reducing the power consumption formanufacturing PDPs and for electric furnaces because of a reduction innumber of sintering processes.

The invention reduces waste disposal of the glass substrates, even ifthey are not reused for new PDPs, since removal of the lead componentsfrom the panels allows them to be treated as ordinary glass. There isalso an advantage that the panels can be recycled as glass cullet in anyglass manufacturing factories, as needless to note. Moreover, nonworkingPDPs can be reused for manufacture of glass substrates. Accordingly,effects of the present invention are very environmentally significant,considering that waste disposal of PDPs have a harmful environmentalimpact. Therefore, PDPs are disposed of as industrial waste.

What is claimed is:
 1. A plasma display panel configured for ease ofdisassembly comprising: a display area, a front plate and a back platewith ribs disposed inside the display area, the ribs maintaining a spacetherebetween, and a component located between the front and back plates,the component disposed separate from and outside the display area,wherein said component comprises a material selected from the groupconsisting of a metal material and a non-glass ceramic materialexpandable to widen the space between said front and back plates uponheating.
 2. The plasma display panel according to claim 1, wherein abonding material connects the front and back plates, and said componentmaintains the width of the predetermined space between said two platesat a temperature equal to or higher than the softening temperature ofsaid bonding material.
 3. The plasma display panel according to claim 1,wherein a bonding material connects the front and back plates, and saidcomponent increases the width of the predetermined space between saidtwo plates at a temperature equal to or higher than the softeningtemperature of said bonding material.
 4. A plasma display panelconfigured for ease of disassembly comprising: a display area, a frontplate and a back plate with ribs disposed inside the display area, theribs maintaining a space therebetween, and a component located betweenthe front and back plates, the component disposed separate from andoutside the display area, wherein said component comprises a materialselected from the group consisting of a metal material and a non-glassceramic material expandable to widen the space between said front andback plates upon heating, wherein said component is in contact with onesaid front plate and back plate and maintains a gap with the other ofsaid front plate and said back plate under an ordinary room ambientoperating temperature, said component coming into contact with both ofsaid plates when said plasma display panel is heated beyond saidoperating temperature.
 5. A plasma display panel comprising a frontplate; a back plate bonded to the front plate at the peripheries of saidplates, thereby defining a bonded portion; a display screen locatedbetween the two plates within the bonded portion; and a groove in atleast one of the front and back plates for communicating between thebonded portion and the periphery of said front and back plates, thegroove entirely surrounding the display screen within the bondedportion.
 6. A plasma display panel comprising a front plate; a backplate bonded to the front plate at the peripheries of said plates,thereby defining a bonded portion; a display screen located between thetwo plates within the bonded portion; and a groove in one of a frontplate and a back plate thereof, said groove being located away from thebonded portion of said front and back plates and the display screen. 7.The plasma display panel according to claim 6, wherein one of saidplates is provided with at least a first electrode and a dielectriclayer, and said groove is provided in parallel with a longitudinaldirection of said first electrode on said plate.
 8. The plasma displaypanel according to claim 7, wherein one of said plates is provided withat least a second electrode and a rib, and said groove is provided inparallel with a longitudinal direction of said second electrode on saidplate.